Sludge Study : Marine Biologists Eager for an End to Sewage Deposits

Seven miles from the beaches of Santa Monica Bay, the ocean floor is covered with a smelly blanket of gurgling ooze. Nothing survives in the black jelly except a few notorious worms and a clam with no stomach that feeds on poison sulfur gas.

No Steven Spielberg creation, this reeking wasteland is among the foulest pieces of U.S. coastal shelf, the most dramatic legacy of 30 years of ocean sewage disposal off Los Angeles.

“It is like the Black Hole of Calcutta down there--really nasty,” said John Dorsey, a marine biologist for the City of Los Angeles.

But by year end, Los Angeles must stop depositing the main culprit--sludge, a noxious form of condensed sewage--and scientists are taking advantage of the rare chance for some deep-water environmental detective work.

Eager to Watch

The Los Angeles sludge pipeline is the last active ocean dump in the country, and marine biologists are eager to watch what occurs as the ocean floor tries to shake the toxic effects of sewage and recover its natural state.

Scientists from the National Oceanic and Atmospheric Administration, the Environmental Protection Agency and other groups have been waiting more than two years for Los Angeles to stop the sludge discharge, which violates federal clean water laws. The study will provide new information on the sea floor’s ability to survive the toxic shock of accumulated sludge and is expected to shape future policy on sewage disposal.

Los Angeles was first ordered to stop dumping in 1985. But the city’s engineers have been unable to coax their $233-million alternative, an innovative process of burning sludge, into working. After several deadlines were missed, a federal court agreement finally set Dec. 31 as the final day of sludge dumping.

In fact, the city beat the deadline and last month closed the sludge pipeline from the Hyperion sewage plant near El Segundo. The shut-off was billed as temporary, but Los Angeles officials said they will leave the pipe off unless a serious snarl occurs. The sludge-burning process is still not working--and engineers cannot say when it ever will--but the sludge is being trucked inland to landfills and buried.

Based on earlier studies, biologists said they expect that the 2 1/2-mile-long sludge field at the mouth of the Los Angeles pipeline will show signs of life again within a year. But they are less certain about the area returning to normal any time soon.

“We’ve already seen what happens after 30 years of ocean disposal,” said Bruce E. Thompson, biologist for the Southern California Coastal Water Research Project, who is conducting the study with Dorsey and other city biologists. “Now we want to document what happens when you turn it off. We aren’t sure what will happen.”

75 Animal Species

Normally, mud taken from the ocean floor off Southern California writhes with 75 species of animals: small worms and urchins, plus larger crabs, prawns and starfish. They slither and skitter across the bottom and serve as food for several kinds of fish, including the white croaker and Dover sole popular with local fishermen.

After 30 years of sludge discharge, a wide area of ocean floor on the coastal shelf has been changed. Away from the sludge pipe, the array of bottom life has been altered, but not dramatically. One kind of clam, the parvilucina, even seems to thrive on the sewage, growing to four times the size found in cleaner sediment.

But it is much different inside the sludge field, which begins at the mouth of the pipeline, 320 feet below the sailboats and gray whales that cruise the surface of Santa Monica Bay. The field coats the bottom for 2 1/2 miles down Santa Monica Canyon, a steep chasm in the ocean floor.

Sediment hauled to the surface bubbles with hydrogen sulfide, a sulfurous byproduct of decaying sludge that is poisonous to most marine life. Two weeks ago, the crew collecting sludge samples on the Marine Surveyor, the city’s 65-foot test boat, became ill from the noxious fumes.

“The stuff is pitch black, with a very, very strong odor like rotten eggs,” Thompson said. “It makes you woozy. We have to be very careful with it.”

The levels of hydrogen sulfide in the sludge field are 200 to 300 times higher than in ordinary sea mud. The sulfur environment, Thompson and Dorsey found, kills all but a select few tiny scavenger worms found at all of the world’s worst contamination sites. They thrive on organic waste, such as sewage, and disappear when the areas are cleaned up.

The only other animal found in the sulfur zone is the solemya clam, called the “gutless wonder” by admiring biologists. It has evolved with no stomach, and survives thanks to a bacteria that digests the sulfur into food.

But the sludge is a witch’s brew of chemicals and urban debris--a toxic soup, Thompson said, that makes it hard to predict how fast recovery will occur.

Sewer Mains

Los Angeles sewage is mostly household and industrial waste--more than 90% water as it runs through the sewer mains toward the ocean. At the Hyperion treatment plant, the water is separated from the solid matter, which is condensed into sludge.

Before the sludge is pumped onto the sea bottom, it is processed in “digesters” that essentially cook out much of the bacteria and organic material. It is also spun in a centrifuge to remove even more water, then pumped down to the sea bottom through a 20-inch pipeline. Before the pipeline was turned off, Los Angeles discharged about 4.2 million gallons of sludge on a typical day.

Wood slivers, hair and watermelon seeds often survive the digesters and wind up intact in the muck on the ocean floor. Biologists picking through the mess looking for animals sometimes mistake tomato seeds for ostracods, a small crustacean that lives on the ocean floor.

Sludge is also contaminated with DDT, PCBs and toxic metals such as silver, cadmium and nickel. In one year, the Los Angeles sludge pipe dumped 2,300 tons of oil and grease, 59 tons of copper and 12 tons of lead on the ocean floor.

Dorsey said the accumulation of toxic materials should start to dissipate now that the dumping has stopped. But scientists do not know enough about the conditions in such deep water to predict how fast, and they cannot predict when the sea life at 320 feet will return to anything close to normal.

With no new sludge being dumped, they expect fresh seawater to quickly begin oxidizing the poisonous hydrogen sulfide. Then the sludge layer will start to be covered by clean, healthy sediments washed down the ocean shelf from closer to shore.

Once the sludge field becomes livable again, Dorsey and Thompson predict, worms and other small animals from the fertile sea bottom nearby will venture in and seed new colonies. That could begin within a year, they said. Eventually, the clams and brittlestars so abundant elsewhere in Santa Monica Bay should start to reappear.

But the sea bottom most likely will not be declared recovered for several years, they said, because it could take that long for lingering effects of contamination to disappear.

The sea bottom will be considered recovered when the marine life and bottom sediments in the dead area resemble the sea bottom off Malibu, about eight miles away.

Malibu will be used for comparison, Dorsey said, because it is far enough from the sludge field to escape heavy contamination, but close enough to have background levels of contaminations typical of the coast off urban areas of Southern California.

Pollutants such as DDT, PCBs and toxic metals are found all along the Southern California coast, but they are highest in Santa Monica Bay and the waters off Long Beach and Orange County.

Recovery of the sea bottom could be slow also because Los Angeles sludge is not the only source of contamination.

Los Angeles, which treats the sewage for about 30 cities and other jurisdictions, also discharges partially treated waste water from the Hyperion plant into Santa Monica Bay through a pipeline that ends three miles from the sludge outfall. The Los Angeles County Sanitation Districts discharge partially treated waste water off Palos Verdes, and the Orange County Sanitation Districts pipe waste water into the Pacific off Dana Point.

Currents have distributed the sewage across a wide area of ocean and sea bottom, and the runoff from storm drains--which flow unchecked into the ocean--has delivered even more toxic materials into Santa Monica Bay and the waters off Long Beach and Orange County.

The toxics either settle to the bottom with the sludge or become attached to minute particles of sewage suspended in the ocean. Some is ingested by fish that eat the bottom-dwelling creatures.

White croaker, a popular sport fish, “is probably the most contaminated species we have,” Dorsey said. The croakers like to feed on the worms that grow around the sewage discharge pipes and end up ingesting a lot of the bottom sediment. The DDT and PCBs in the sludge then get trapped in the fatty tissue of the croakers.

OCEAN DUMP

Area to be studied to determine how fast ocean recovers after sludge-dumping ends.

Area of worst contamination.

Sludge pipe empties seven miles from shore, 97 meters deep, at rim of Santa Monica Canyon.